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PSADT Predicts Survival In Hormone
Refractory Prostate Cancer
(August 2005)
PSADT continues to reflect the biology of the disease in
HRPC because the rate of growth of malignancy remains essentially constant
(log linear) during this period. It can serve as a guide in the usually
difficult decision regarding intervention, which always involves a
tradeoff between the toxicity of the treatment versus its benefit.
In the review cited above from Clinical Prostate Cancer
the data also allowed a prediction for prostate cancer-specific
survival in men with AIPC. PSADTs of <3, 3-6, 6-12, and >12 months were
associated with survival times of 12.6, 38.4, 71.2 and 107.5 months.
Three ASCO abstracts addressed this issue:
1) #4631 (2005) presented the Stanford data on 90 men. 82%
had objective metastases and 60% were symptomatic. They reported that
those with PSADT >3 months respond better to
chemotherapy and had a superior survival. A PSADT of < 1 month
predicted for the early development of symptoms.
2) #4551 (2005) reported data on 202 metastatic HRPC
patients and correlated the PSADT during the three months prior to
chemotherapy with overall survival. The median PSADT for the entire group
was 44 days and a faster value was associated with survival of 14.3 months
compared to 25.6 months for a longer DT.
3) #4504 (2004) presents an analysis by Crawford et al. of
data from 499 men in the SWOG 99-16 trial comparing mitoxanthrone/
prednisone with docetaxel/estramustine based on a determination of the
PSADT during the first three months of chemotherapy. Their
findings: categorization by PSA velocity [a measure of PSA dynamics
related to PSADT] best predicted mortality: “After adjustment for PSA
velocity, treatment was no longer associated with mortality”...”with odds
of failing nearly quadrupling with each unit of increase of PSA velocity.”
An important implication to be drawn from these data is
that the PSADT needs to be considered in the design and interpretation of
clinical trials.
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